Heavy metals contamination of waters worldwide and their perspectives for remediation through ecotechnologies

The contamination of water resources and water bodies with noxious pollutants, particularly heavy metals is becoming an irrefutable social and environmental concern worldwide. The stability and bio-accumulative property of most of these metals is a big hurdle in the assessment of their safe limits in the ecosystem. Although a limited amount of these metals such as nickel, zinc, cobalt, copper, and manganese have a role in biological metabolic processes, toxicity can be caused if these metals are prevalent in high quantities. However, many of these metals like arsenic, cadmium, lead, and mercury are quite injurious and pose serious health threats. In the past few years, several technologies have been formulated to remediate contaminated water from toxic metals. In contrast to conventional water treatment techniques such as chemical precipitation, ion exchange, and electrochemical deposition methods, numerous eco-friendly technologies have been found successful in the decontamination of polluted waters worldwide. In this regard, techniques such as biofiltration, biosorption, anaerobic treatment, and bioreactors are among the extensively employed ecotechnologies for the extraction of virulent metals from water. This chapter briefly appraises the sources, toxicity, and sustainable environmentally sound remediation methods for heavy metals withdrawal from polluted water.